Isolating Chemical Exchange Contrast from Amide and Amine Protons in the Presence of Asymmetric Macromolecular Magnetization Transfer with Off-Resonance Spin Locking at 3T in the Human Brain

Rachel Scheidegger¹, ², David C. Alsop¹, ³

We present spin-locking RF preparations schemes optimized to generate chemical exchange saturation transfer (CEST) contrast with reduced errors from multiple exchangeable protons and intrinsic magnetization transfer (MT) asymmetry for human imaging at 3T. Tuning both the spin-locking power and duration can be used to maximize signal from either amide or amine protons. We demonstrate, in healthy volunteers, how these methods allow clear and robust measurement of the amine proton peak with reduced MT asymmetry which could improve the feasibility of quantifying exchange rates in-vivo and measuring pH.